Anti-siphon anti-backflow valve



July 4, 1961 G. SMITH -SIPI-1ON ANTI-BACKFLOW VALVE Filed Nov. 1. 1956ANTI United States Patent 2,990,843 ANTI-SIPHON ANTI-BACKFLOW VALVEGeorge L. Smith, 6450 W. River Parkway, Milwaukee, Wis. Filed Nov. 1,1956, Ser. No. 619,832 1 Claim. (Cl. 137-218) This invention relates tovalves and refers more particularly to anti-siphon anti-backflow valvesof the types used in situations where protection must be providedagainst the ilow of contaminated water back into the supply system. Oneinstance where such backilow could'ocour and for which the valve of thisinvention was especially designed, is in connection with drinking cupsprovided in dairy barns. These cups usually consist of a bowl connectedto the water supply system below the water level in the bowl, by a valveoperable by pressure which the cow exerts with its muzzle against alever located in the bowl. Since farms are generally equipped withindividual water systems, pressure failures are not uncommon and, whenthey occur, there is a strong possibility that water from the drinkingcups of the barn is apt to flow back or be siphoned into the supplysystem, unless some means 1s provided to prevent this occurrence.

It is recognized that anti-siphon anti ba-ckflow valves per se are notnew, but valves of this type heretofore available, have not lentthemselves well to the particular lnstallanon above outlined, especiallysince they were not capable of being easily and quickly disassembled forcleaning purposes, and' also because they 'were not entirely reliable.

-The present invention, therefore, has as its purpose to provide ananti-siphon anti-backflown valve which is simply constructed and easilydisassembled for cleaning, and, in addition, is unfailingly reliable inoperation.

Another object of this invention is to provide a valve of the characterdescribed which consists of but a few easily manufactured parts. 7

Still another and very important object of this inven tion is to providea valve of the character described wherein the valve seats are not onlyrenewable, but in fact easily and quickly entirely replaceable, to whichend the valve is so constructed that the valve seat unit is readily andeasily disassembled from the valve body. 7

With the above and other objects in view, which will appear as thedescription proceeds, this invention resides in the novel construction,combination and arrangement of parts substantially as hereinafterdescribed and more particularly defined by the appended claims, it beingunderstood that such changes in the precise embodiment of thehereindisclosed invention may bemade as come within the scope of theclaim.

The accompanying drawing illustrates one complete example of thephysical embodiment of the invention constructed according to the bestmode so far devised for the practical application of the principlesthereof and in which:

FIGURE 1 is a view in longitudinal section through the valve embodyingthis invention, and illustrating the same connected in a supply line;and

FIGURE 2 is an exploded perspective view of the various components ofthe valve.

Referring now more particularly to the accompanying drawing, the numeral5 designates the body of the valve which, as shown, has a substantiallyT-shaped formation with the head thereof providing a main passage 6which must be vertical when the valve is in position of use, and thestern of the T providing a lateral branch passage 7. The opposite endsof the passage 6 are open and are bored, as at 8-8, and counterbored asat 9-9, the junctions between the bores and counterbores providingoppositely facing shoulders 10-10. The bores and Patented July 4, i961counterbores are exactly coaxial, and attention is directed to the factthat the upper bore 8 and its counterbore 9 are of larger diameter thanthe lower bore 8 and counterbore 9.

Readily removably received in the upper and lower ends of the verticalpassage 6, are upper and lower valve seat units 11 and 11',respectively. Each of these valve seat units comprises a spider havingan annulus 12, a hub 13, and radiating arms 14 connecting the hub andannulus. The outer diameter of the annulus is of a size to be snugly,though freely, received in its respective bore 8-8, so that the twounits are held in exactly coaxial alignment with their hubs facing inopposite directions and the inner edges of the annuli facing one anotherto provide upper and lower valve seats 15-15'.

The axial position of the valve seat units is defined by circumferentialflanges 16-16 extending from their annuli and clamped against theshoulders 10-10 by tubular retaining members 17-17 threaded into thecounterbores 9-9. Leak proof connections between the valve seat unitsand the valve body are provided by 0- ring type gaskets 18-18 confinedbetween the retaining members and the shoulders. Accordingly, the onlyc0mmunication between the lateral branch 7 of the valve whichconstitutes the liquid outlet, and either the upper or lower ends of themain branch 6, is through the ports defined by the annuli 12, and theseports are controlled by a valve spool indicated by the numeral 21.

An important feature of this invention is that the upper port, formed bythe annulus of the upper valve seat unit, is larger than the lower port.In fact, it has been found that the upper port should be at least oneand one-half times as large as the lower port. Unless this difference inport areas is maintained, there is danger that the valve will notrespond properly to a condition demanding closure of the lower port. Forinstance, if the port areas are substantially the same, and certainly ifthe upper port has a smaller area than the lower port, the valve spooltends to .float in an unseated condition permitting contaminated waterto be drawn into the supply system when the pressure thereof drops.

Assurance that the valve seat units will be correctly assembled into thevalve body with the unit having the largest port at the top, is obtainedby the difierence in diameters of the bores 8-8 and the correspondingdiiference in size of the two units.

The valve pool 21 has two oppositely facing upper and lower valve discs22-22, respectively cooperable with the valve seats 15-15'. The spool isfreely movably supported between the valve seats by stems 23-23projecting from the discs and slidably received in the bores of the hubs1-3 of the valve seat units. The two discs are, of course, rigidlyconnected together, and their seating surfaces are conical, as shown,while the valve seats 15-15 preferably have sharp knife edges. The axialdistance between the two discs is substantially less than the distancebetween the upper and lower valve seats so that only one disc van beseated at a time.

To assure prompt and easy action of the valve, the entire valve spoolunit including its stems, is of such proportions and Weight that thespecific gravity thereof is substantially equal to that of the liquidwith which the valve is to be used.

The valve spool unit may be made of many different materials, butthermo-plastics are exceptionally well adapted to the purpose, andbecause of its high impact strength, Super Dylon is particularly good.

Prompt lifting of the valve spool to its position allowing liquid flowthrough the valve body and completely blocking the upper port is assuredby an inwardly extending lip 24 on the inside of the valve body. Thislip is located to be substantially opposite the lower valve disc 22 whenthe valve spool is in its lifted position, and, by virtue of its slopingunderside, directs the incoming water upwardly against the underside ofthe valve spool.

Attention is directed to the fact that the lower valve seat is at anelevation above the bottom of the lateral branch passage 7. Because ofthis construction, it follows that water flowing along the bottom of thebranch 7 cannot drain by gravity back into the inlet. This feature isespecially significant in the event of imperfect seating of the lowervalve disc when the valve spool is in its lower position disconnectingthe liquid inlet and outlet.

The tubular retaining members 1717', and also the lateral passage 7, areinternally threaded to permit the attachment of pipes thereto and, whenthe valve is in service, the lower end of the vertical passage isconnected to a water supply pipe 19, and the lateral passage isconnected to a water outlet pipe 20. The upper retaining member 17 neednot have a pipe connected thereto, but to protect the valve againsthaving something drop into it, a goose neck air vent (not shown) ispreferably secured thereto.

Operation When the valve is in service, it must be mounted in theposition shown in FIGURE 1 with its main through passage 6 exactlyvertical and with the larger valve seat 15 uppermost. When so arranged,water entering through the line 19 holds the valve spool unit in itsraised position shown in FIGURE 1, tightly closing the air vent andallowing the water to flow out through the discharge line 20, as long asthe pressure is normal. The instant the pressure of the incoming waterdrops below the normal minimum and backflow or siphoning becomes likely,the valve spool unit immediately leaves the upper seat 15 allowing airat atmospheric pressure to rush into the water outlet line 20 andthereby block backflow even before the valve spool seats itself upon thelower seat 15 to close ofl? communication between the liquid inlet andoutlet. Drainage of contaminated water from a drinking cup or otherreceptacle supplied by the line 20, back into the supply system, is thusprecluded.

From the foregoing description taken in connection with the accompanyingdrawing, it will be readily apparent to those skilled in the art, thatthis invention provides an anti-Syphon anti-backflow valve which notonly is entirely unprecedented in reliability and simplicity ofconstruction, but, in addition, consists of but a few parts which may beeasily and completely disassembled.

What is claimed as my invention is:

An anti-siphon anti-backflow valve, comprising: a hollow body having astraight through vertical passage with an upwardly opening counterboreat its top, the bottom of the counterbore forming an upwardly facingshoulder; means at the lower end of the body defining a water inlet andproviding for the attachment of the body to a water supply pipe; meanson the body defining a water outlet leading from the side of the bodydirectly adjacent to and below said shoulder; means in the lower portionof the body providing an upwardly facing horizontal valve seat betweenthe water inlet and outlet, concentric with the upwardly openingcounterbore and at a level between the top and bottom of the wateroutlet, the diameter of the port through said valve seat' beingconsiderably smaller than the diameter of the counterbored upper end ofthe vertical passage; a spider having a bored hub and an annulusconnected with the hub by radiating spaced arms, the peripheral portionof the annulus being seated upon the upwardly facing shoulder and theinner portion of the annulus extending into the vertical passage andproviding a downwardly facing horizontal valve seat substantially at thelevel of the shoulder and normal to the axis of the bore through the hubof the spider and coaxial with said axis and with that of the upwardlyfacing valve seat, the diameter of the port through said downwardlyfacing valve seat being decidedly greater than the diameter of the portthrough the upwardly facing valve seat, and the radiating spaced arms ofthe spider extending upwardly and inwardly from the annulus to locatethe bored hub of the spider at a substantial elevation above the top ofthe annulus; a tubular retainer detachably secured in the counterboreand bearing down upon the annulus to clamp the same against the shoulderand thereby readily removably hold the spider in place; a molded plasticvalve spool having a one piece body with a large diameter upper portionshaped to have sealing engagement with the downwardly facing valve seatand a smaller diameter lower portion shaped to have sealing engagementwith the upwardly facing valve seat, said large diameter upper portionbeing the largest diameter part of the spool and said large and smalldiameter portions being coaxial and spaced apart a distance less thanthe diameter of the large diameter upper portion and less than the axialdistance between the valve seats so that the valve spool can engage onlyone of the seats at a time, the large diameter of the port through thedownwardly facing valve seat and its close proximity to the water outletassuring large unrestricted communication between the open top of thevertical passage and the water outlet upon disengagement of the largediameter upper portion of the valve spool from its seat; and a stemprojecting coaxially up from the valve spool and slidably received inthe bore of the spider hub to guide and constrain the valve spool toaxial vertical motion, the plastic material of which the valve spool ismade having a specific gravity not in excess of that of water.

References Cited in the file of this patent UNITED STATES PATENTS746,402 Sutton Dec. 8, 1903 1,402,718 Armstrong et a1. Jan. 3, 19221,660,634 Thomas Feb. 28, 1928 2,252,164 Cantor Aug. 12, 1941 2,301,276Gussick Nov. 10, 1942 2,638,243 Davies May 12, 1953 2,655,171 CantorOct. 13, 1953 2,726,104 Boitnott Dec. 6, 1955 2,730,117 Svirsky Jan. 10,1956 2,814,304 Sloan Nov. 26, 1957 2,850,034 Svabek Sept. 2, 1958

